The present invention relates in general to spring elements, and, more particularly, to a spring element for use in an apparatus for attaching to a plurality of contacts of a semiconductor.
Unpackaged or bare semiconductor dies are used to construct multi-chip modules (MCMs) and other electronic devices. Unpackaged dies must be tested and burned in during the manufacturing process to certify each die as a known good die. This has led to the development of temporary packages that hold a single bare die for testing and burn-in. The temporary packages provide the electrical interconnection between the test pads on the die and external test circuitry. Exemplary temporary packages are disclosed in U.S. Pat. Nos. 5,302,891, 5,408,190 and 5,495,179 to Wood et al., which are herein incorporated by reference.
Typically, this type of temporary package includes an interconnect having contact members that make a temporary electrical connection with the test pads on the die. The temporary package can also include an attachment device that presses the die against the interconnect. The attachment device may include a clamping device that attaches to a package base and a spring element that presses the die against the interconnect. The configuration of the spring element is dependent on a number of factors. The spring element must be able to withstand relatively high compressive forces and relatively high bum-in temperatures without experiencing compression set. Further, the dimensions of the spring element must be such that it is compatible with the temporary package. Finally, the spring element must be able to withstand the amount of pressure required for pressing the die against the interconnect without causing an excessive amount of force to be transferred to the die, and thus damaging the same.
Accordingly, there is a need for a spring element which is compatible with the temporary packages and environment used to test and burn-in semiconductor. Preferably, such a spring element would be reusable and inexpensive to manufacture.
The present invention meets this need by providing a spring element having a modulus of elasticity which may be adjusted according to the required environment. Material may be removed from or added to the spring element to change the modulus of elasticity as needed. The shape of the spring element may also be varied to change the modulus of elasticity, the spring constant, and the force transfer capabilities of the spring element.
According to a first aspect of the present invention, a spring element comprises a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. The first elastic member has a plurality of holes formed therein such that the spring element has an overall modulus of elasticity different from the first modulus of elasticity. The spring element may further comprise a second elastic member comprised of a second elastomeric material having a second modulus of elasticity. The second elastic member is positioned in at least one of the plurality of holes formed in the first elastic member such that the overall modulus of elasticity is different from the first and second module of elasticity. The spring element may further comprise a plurality of the second elastic members positioned in a plurality of the plurality of holes in the first elastic member. The first and second elastomeric materials may comprise silicone.
According to another aspect of the present invention, a spring element comprises a first elastic member comprised of silicone having a first modulus of elasticity and a plurality of second elastic members each comprised of silicone having a second modulus of elasticity. The plurality of second elastic members are positioned in each of a plurality of holes in the first elastic member such that the spring element has an overall modulus of elasticity different from the first and second moduli of elasticity.
According to yet another aspect of the present invention, a spring element comprises a first elastic member and a second elastic member. The first elastic member is comprised of a first elastomeric material having a first modulus of elasticity and the second elastic member is comprised of a second elastomeric material having a second modulus of elasticity. The second elastic member is positioned within the first elastic member such that the spring element has an overall modulus of elasticity different from the first and second moduli of elasticity. The spring element may further comprise a plurality of the second elastic members positioned within the first elastic member. The second elastic member may be substantially spherical or elongated. The first elastomeric material may comprise foam-like silicone while the second elastomeric material may comprise substantially solid silicone.
According to another aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. A portion of the first elastomeric material is removed from the first elastic member such that the spring element has an overall modulus of elasticity different from the first modulus of elasticity.
According to a further aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. The first elastic member has a plurality of holes formed therein such that the spring element has an overall modulus of elasticity different from the first modulus of elasticity. The semiconductor may comprise a semiconductor die or a semiconductor die formed within a semiconductor package. The semiconductor package may comprise a package selected from the group consisting of a chip-scale package, a ball grid array, a chip-on-board, a direct chip attach, and a flip-chip.
According to a still further aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including a first elastic member comprised of silicone having a first modulus of elasticity and a plurality of second elastic members each comprised of silicone having a second modulus of elasticity. The first elastic member includes a plurality of holes formed therein with each of the plurality of holes receiving one of the plurality of second elastic members such that the spring element has an overall modulus of elasticity different from the first and second moduli of elasticity.
According to a yet still further aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including an elastic member comprised of an elastomeric material having a modulus of elasticity. A hole is formed in the elastic member such that the spring element has an overall modulus of elasticity different from the modulus of elasticity of the elastomeric material. The elastic member is also shaped so as to engage an outer edge of the semiconductor such that a force applied by the attachment device as the interconnect structure is pressed against the semiconductor is substantially uniform around the semiconductor. The elastic member may be o-ring shaped and comprised of silicone.
According to another aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including a first elastic member and a second elastic member. The first elastic member comprises a first elastomeric material having a first modulus of elasticity and the second elastic member comprises a second elastomeric material having a second modulus of elasticity. The second elastic member is positioned within the first elastic member such that the spring element has an overall modulus of elasticity different from the first and second moduli of elasticity.
According to yet another aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element comprised of a plurality of interwoven threads. The plurality of interwoven threads may comprise silicone.
According to a further aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including an elastic member comprised of an elastomeric material having a modulus of elasticity. At least one cavity is formed in the elastic member such that the spring element has an overall modulus of elasticity different from the modulus of elasticity of the elastomeric material. The elastic member may have a plurality of cavities formed therein. The elastomeric material may be substantially solid.
According to a still further aspect of the present invention, an apparatus for attaching to a plurality of contacts of a semiconductor comprises an interconnect structure comprising a plurality of conductors patterned to match corresponding ones of the plurality of contacts on the semiconductor and an attachment device pressing the interconnect structure against the semiconductor to provide an electrical connection between the plurality of conductors and the corresponding ones of the plurality of contacts. The attachment device comprises a spring element including an elastic member having a variable spring constant. The elastic member may have a triangular or diamond shaped cross-section. The elastic member may have a repeating triangular or diamond shaped cross-section.
According to another aspect of the present invention, a method of making a spring element comprises providing a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. A plurality of holes are formed in the first elastic member to adjust an overall modulus of elasticity of the spring element. The method may further comprise the step of adding a second elastic member comprised of a second elastomeric material having a second modulus of elasticity to one of the plurality of holes so that the overall modulus of elasticity is different from the first and second moduli of elasticity. The method may further comprise the step of adding a plurality of the second elastic members to a plurality of the plurality of holes in the first elastic member. The plurality of holes may be formed by punching, laser drilling or molding the first elastic member.
According to yet another aspect of the present invention, a method of making a spring element comprises providing a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. A plurality of holes are wet drilled in the first elastic member to adjust an overall modulus of elasticity of the spring element.
According to a further aspect of the present invention, a method of making a spring element comprises providing a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. A plurality of holes are wet drilled in the first elastic member to adjust an overall modulus of elasticity of the spring element. One of a plurality of second elastic members are then added to each of the plurality of holes. Each of the plurality of second elastic members is comprised of a second elastomeric material having a second modulus of elasticity such that an overall modulus of elasticity of the spring element is different from the first and second moduli of elasticity.
According to a still further aspect of the present invention, a method of making a spring element comprises providing a first elastic member comprised of a first elastomeric material having a first modulus of elasticity. Second elastic member composed of a second elastomeric material having a second modulus of elasticity is formed in the first elastic member such that the spring element has an overall modulus of elasticity different from the first and second moduli of elasticity. The method may further comprise the step of forming a plurality of the second elastic members within the first elastic member.
Accordingly, it is an object of the present invention to provide a spring element which is compatible with the temporary packages and environment used to test and burn-in semiconductors. It is another object of the present invention to provide a spring element which is reusable and inexpensive to manufacture. Other features and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.